Comparative Analysis on Artificial Freezing Design Scheme of Vertical Underground Garage

Based on 7m lengthx7m weightx50m depth vertical underground garage of old residence communities in Shanghai China, the new article ground freezing (AGF) method-Box-frozen method was studied. The elastic theory calculation and numerical simulation showed that the thickness of straight (hq) and bottom (hd) frozen wall are 2.8m and 10m respectively, which can meet load bearing and water insulation requirements. Three artificial freezing design schemes and parameters were proposed according to different freezing hole layout, namely, 1) double row holes and cutting bottom holes;2) double row holes and leave bottom holes;3) single row holes and leave bottom holes. Evolution law of temperature field of different Box-frozen design schemes was checked by numerical simulation. The results showed that, during maintenance freezing period, both of double row holes and cutting bottom holes and single row holes and leave bottom holes schemes appear thaw phenomenon at bottom of frozen wall while double row holes and leave bottom holes stops thaw tendency basically. Three Schemes are compared in four aspects including construction period, cost, excavation difficulty and risks, which prove that double row holes and leave bottom holes scheme are a most suitable article ground freezing method due to less construction period and low risk.